Known Affected Releases

10.2(1)

Description (partial)

Symptom:
78XX model ip phones and has configured external services on third party server to use hostname in the URL. Destination server should internally resolve the hostname and provide proper HTTP response. Events should happen in this order: Service list is requested via HTTP (can be from CUCM or third party server). 200OK is sent to IP Phone with a service in hostname format. Hostname is resolved through DNS and should then send the HTTP request with URI in hostname format.
However, for this phone model only, we see that the phone reaches DNS to resolve the service hostname and then modify the service URI to use IP address instead of hostname.
This is causing problem to the CU as third party server expects to get hostname in service URI.
Conditions:
CUCM Version - 10.5.1
Cisco IP Phone Model - 7841
Cisco IP Phone FW version - sip78xx.10-2-1SR1